Hello. We have had this problem for several years and each year the problem gets worse. We have a high velocity a/c system that runs completely separate from our heating system. We have a large house, there there are two different A/C systems installed. One in the basement and one in the attic. The problem is on the 2nd floor with the attic system. The upstairs vents, which are many small round circles in the ceiling, blow out fowl smelling sewer air. It comes and goes, but 80-90% of the time these vents are blowing out smelly sewer gas air. The whole upstairs smells like a sewer after a while. Don't know if this is another clue but sometimes the air that blows out is on the warmer side, other times it's cold. If the sewer smell isn't coming out, then it smells musty and sometimes moldy smelling? Hard to describe.

Another clue? During non summer months when we don't use the air conditioning, when it rains heavily, snows heavily, or on windy days, the smell comes through the a/c vents.

PLEASE HELP! I am no longer able to sleep in my bedroom upstairs because of the smell. Thank you.

roselle1963 -> Hello. We have had this problem for several years and each year the> problem gets worse. We have a high velocity a/c system that runs> completely separate from our heating system. We have a large house, there> there are two different A/C systems installed. One in the basement and one> in the attic. The problem is on the 2nd floor with the attic system. The> upstairs vents, which are many small round circles in the ceiling, blow out> fowl smelling sewer air. It comes and goes, but 80-90% of the time these> vents are blowing out smelly sewer gas air. The whole upstairs smells like> a sewer after a while. Don't know if this is another clue but sometimes> the air that blows out is on the warmer side, other times it's cold. If> the sewer smell isn't coming out, then it smells musty and sometimes moldy> smelling? Hard to describe.> > Another clue? During non summer months when we don't use the air> conditioning, when it rains heavily, snows heavily, or on windy days, the> smell comes through the a/c vents.> > PLEASE HELP! I am no longer able to sleep in my bedroom upstairs because> of the smell. Thank you.